/**
 *    Copyright (c) 2014-2019 CK.
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package com.github.fartherp.framework.common.util;

import java.math.BigDecimal;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.List;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * code convert tools
 * @author CK
 * @date 2015/6/30.
 */
public class ISOUtil {
    /**
     * All methods in this class are static, so there's usually no need to instantiate it
     * We provide this public constructor in order to deal with some legacy script integration
     * that needs an instance of this class in a rendering context.
     */
    public ISOUtil() {
        super();
    }

    public static final String[] hexStrings;

    static {
        hexStrings = new String[256];
        for (int i = 0; i < 256; i++) {
            StringBuilder d = new StringBuilder(2);
            char ch = Character.forDigit((byte) i >> 4 & 0x0F, 16);
            d.append(Character.toUpperCase(ch));
            ch = Character.forDigit((byte) i & 0x0F, 16);
            d.append(Character.toUpperCase(ch));
            hexStrings[i] = d.toString();
        }

    }

    /**
     * Default encoding (charset) for bytes transmissions over network
     *
     * @deprecated use {@link #CHARSET} instead
     */
    public static final String ENCODING = "ISO8859_1";

    /**
     * Default charset for bytes transmissions over network
     */
    public static final Charset CHARSET = Charset.forName("ISO8859_1");

    public static final byte[] EBCDIC2ASCII = new byte[]{
            (byte) 0x0, (byte) 0x1, (byte) 0x2, (byte) 0x3,
            (byte) 0x9C, (byte) 0x9, (byte) 0x86, (byte) 0x7F,
            (byte) 0x97, (byte) 0x8D, (byte) 0x8E, (byte) 0xB,
            (byte) 0xC, (byte) 0xD, (byte) 0xE, (byte) 0xF,
            (byte) 0x10, (byte) 0x11, (byte) 0x12, (byte) 0x13,
            (byte) 0x9D, (byte) 0xA, (byte) 0x8, (byte) 0x87,
            (byte) 0x18, (byte) 0x19, (byte) 0x92, (byte) 0x8F,
            (byte) 0x1C, (byte) 0x1D, (byte) 0x1E, (byte) 0x1F,
            (byte) 0x80, (byte) 0x81, (byte) 0x82, (byte) 0x83,
            (byte) 0x84, (byte) 0x85, (byte) 0x17, (byte) 0x1B,
            (byte) 0x88, (byte) 0x89, (byte) 0x8A, (byte) 0x8B,
            (byte) 0x8C, (byte) 0x5, (byte) 0x6, (byte) 0x7,
            (byte) 0x90, (byte) 0x91, (byte) 0x16, (byte) 0x93,
            (byte) 0x94, (byte) 0x95, (byte) 0x96, (byte) 0x4,
            (byte) 0x98, (byte) 0x99, (byte) 0x9A, (byte) 0x9B,
            (byte) 0x14, (byte) 0x15, (byte) 0x9E, (byte) 0x1A,
            (byte) 0x20, (byte) 0xA0, (byte) 0xE2, (byte) 0xE4,
            (byte) 0xE0, (byte) 0xE1, (byte) 0xE3, (byte) 0xE5,
            (byte) 0xE7, (byte) 0xF1, (byte) 0xA2, (byte) 0x2E,
            (byte) 0x3C, (byte) 0x28, (byte) 0x2B, (byte) 0x7C,
            (byte) 0x26, (byte) 0xE9, (byte) 0xEA, (byte) 0xEB,
            (byte) 0xE8, (byte) 0xED, (byte) 0xEE, (byte) 0xEF,
            (byte) 0xEC, (byte) 0xDF, (byte) 0x21, (byte) 0x24,
            (byte) 0x2A, (byte) 0x29, (byte) 0x3B, (byte) 0x5E,
            (byte) 0x2D, (byte) 0x2F, (byte) 0xC2, (byte) 0xC4,
            (byte) 0xC0, (byte) 0xC1, (byte) 0xC3, (byte) 0xC5,
            (byte) 0xC7, (byte) 0xD1, (byte) 0xA6, (byte) 0x2C,
            (byte) 0x25, (byte) 0x5F, (byte) 0x3E, (byte) 0x3F,
            (byte) 0xF8, (byte) 0xC9, (byte) 0xCA, (byte) 0xCB,
            (byte) 0xC8, (byte) 0xCD, (byte) 0xCE, (byte) 0xCF,
            (byte) 0xCC, (byte) 0x60, (byte) 0x3A, (byte) 0x23,
            (byte) 0x40, (byte) 0x27, (byte) 0x3D, (byte) 0x22,
            (byte) 0xD8, (byte) 0x61, (byte) 0x62, (byte) 0x63,
            (byte) 0x64, (byte) 0x65, (byte) 0x66, (byte) 0x67,
            (byte) 0x68, (byte) 0x69, (byte) 0xAB, (byte) 0xBB,
            (byte) 0xF0, (byte) 0xFD, (byte) 0xFE, (byte) 0xB1,
            (byte) 0xB0, (byte) 0x6A, (byte) 0x6B, (byte) 0x6C,
            (byte) 0x6D, (byte) 0x6E, (byte) 0x6F, (byte) 0x70,
            (byte) 0x71, (byte) 0x72, (byte) 0xAA, (byte) 0xBA,
            (byte) 0xE6, (byte) 0xB8, (byte) 0xC6, (byte) 0xA4,
            (byte) 0xB5, (byte) 0x7E, (byte) 0x73, (byte) 0x74,
            (byte) 0x75, (byte) 0x76, (byte) 0x77, (byte) 0x78,
            (byte) 0x79, (byte) 0x7A, (byte) 0xA1, (byte) 0xBF,
            (byte) 0xD0, (byte) 0x5B, (byte) 0xDE, (byte) 0xAE,
            (byte) 0xAC, (byte) 0xA3, (byte) 0xA5, (byte) 0xB7,
            (byte) 0xA9, (byte) 0xA7, (byte) 0xB6, (byte) 0xBC,
            (byte) 0xBD, (byte) 0xBE, (byte) 0xDD, (byte) 0xA8,
            (byte) 0xAF, (byte) 0x5D, (byte) 0xB4, (byte) 0xD7,
            (byte) 0x7B, (byte) 0x41, (byte) 0x42, (byte) 0x43,
            (byte) 0x44, (byte) 0x45, (byte) 0x46, (byte) 0x47,
            (byte) 0x48, (byte) 0x49, (byte) 0xAD, (byte) 0xF4,
            (byte) 0xF6, (byte) 0xF2, (byte) 0xF3, (byte) 0xF5,
            (byte) 0x7D, (byte) 0x4A, (byte) 0x4B, (byte) 0x4C,
            (byte) 0x4D, (byte) 0x4E, (byte) 0x4F, (byte) 0x50,
            (byte) 0x51, (byte) 0x52, (byte) 0xB9, (byte) 0xFB,
            (byte) 0xFC, (byte) 0xF9, (byte) 0xFA, (byte) 0xFF,
            (byte) 0x5C, (byte) 0xF7, (byte) 0x53, (byte) 0x54,
            (byte) 0x55, (byte) 0x56, (byte) 0x57, (byte) 0x58,
            (byte) 0x59, (byte) 0x5A, (byte) 0xB2, (byte) 0xD4,
            (byte) 0xD6, (byte) 0xD2, (byte) 0xD3, (byte) 0xD5,
            (byte) 0x30, (byte) 0x31, (byte) 0x32, (byte) 0x33,
            (byte) 0x34, (byte) 0x35, (byte) 0x36, (byte) 0x37,
            (byte) 0x38, (byte) 0x39, (byte) 0xB3, (byte) 0xDB,
            (byte) 0xDC, (byte) 0xD9, (byte) 0xDA, (byte) 0x9F
    };
    public static final byte[] ASCII2EBCDIC = new byte[]{
            (byte) 0x0, (byte) 0x1, (byte) 0x2, (byte) 0x3,
            (byte) 0x37, (byte) 0x2D, (byte) 0x2E, (byte) 0x2F,
            (byte) 0x16, (byte) 0x5, (byte) 0x15, (byte) 0xB,
            (byte) 0xC, (byte) 0xD, (byte) 0xE, (byte) 0xF,
            (byte) 0x10, (byte) 0x11, (byte) 0x12, (byte) 0x13,
            (byte) 0x3C, (byte) 0x3D, (byte) 0x32, (byte) 0x26,
            (byte) 0x18, (byte) 0x19, (byte) 0x3F, (byte) 0x27,
            (byte) 0x1C, (byte) 0x1D, (byte) 0x1E, (byte) 0x1F,
            (byte) 0x40, (byte) 0x5A, (byte) 0x7F, (byte) 0x7B,
            (byte) 0x5B, (byte) 0x6C, (byte) 0x50, (byte) 0x7D,
            (byte) 0x4D, (byte) 0x5D, (byte) 0x5C, (byte) 0x4E,
            (byte) 0x6B, (byte) 0x60, (byte) 0x4B, (byte) 0x61,
            (byte) 0xF0, (byte) 0xF1, (byte) 0xF2, (byte) 0xF3,
            (byte) 0xF4, (byte) 0xF5, (byte) 0xF6, (byte) 0xF7,
            (byte) 0xF8, (byte) 0xF9, (byte) 0x7A, (byte) 0x5E,
            (byte) 0x4C, (byte) 0x7E, (byte) 0x6E, (byte) 0x6F,
            (byte) 0x7C, (byte) 0xC1, (byte) 0xC2, (byte) 0xC3,
            (byte) 0xC4, (byte) 0xC5, (byte) 0xC6, (byte) 0xC7,
            (byte) 0xC8, (byte) 0xC9, (byte) 0xD1, (byte) 0xD2,
            (byte) 0xD3, (byte) 0xD4, (byte) 0xD5, (byte) 0xD6,
            (byte) 0xD7, (byte) 0xD8, (byte) 0xD9, (byte) 0xE2,
            (byte) 0xE3, (byte) 0xE4, (byte) 0xE5, (byte) 0xE6,
            (byte) 0xE7, (byte) 0xE8, (byte) 0xE9, (byte) 0xAD,
            (byte) 0xE0, (byte) 0xBD, (byte) 0x5F, (byte) 0x6D,
            (byte) 0x79, (byte) 0x81, (byte) 0x82, (byte) 0x83,
            (byte) 0x84, (byte) 0x85, (byte) 0x86, (byte) 0x87,
            (byte) 0x88, (byte) 0x89, (byte) 0x91, (byte) 0x92,
            (byte) 0x93, (byte) 0x94, (byte) 0x95, (byte) 0x96,
            (byte) 0x97, (byte) 0x98, (byte) 0x99, (byte) 0xA2,
            (byte) 0xA3, (byte) 0xA4, (byte) 0xA5, (byte) 0xA6,
            (byte) 0xA7, (byte) 0xA8, (byte) 0xA9, (byte) 0xC0,
            (byte) 0x4F, (byte) 0xD0, (byte) 0xA1, (byte) 0x7,
            (byte) 0x20, (byte) 0x21, (byte) 0x22, (byte) 0x23,
            (byte) 0x24, (byte) 0x25, (byte) 0x6, (byte) 0x17,
            (byte) 0x28, (byte) 0x29, (byte) 0x2A, (byte) 0x2B,
            (byte) 0x2C, (byte) 0x9, (byte) 0xA, (byte) 0x1B,
            (byte) 0x30, (byte) 0x31, (byte) 0x1A, (byte) 0x33,
            (byte) 0x34, (byte) 0x35, (byte) 0x36, (byte) 0x8,
            (byte) 0x38, (byte) 0x39, (byte) 0x3A, (byte) 0x3B,
            (byte) 0x4, (byte) 0x14, (byte) 0x3E, (byte) 0xFF,
            (byte) 0x41, (byte) 0xAA, (byte) 0x4A, (byte) 0xB1,
            (byte) 0x9F, (byte) 0xB2, (byte) 0x6A, (byte) 0xB5,
            (byte) 0xBB, (byte) 0xB4, (byte) 0x9A, (byte) 0x8A,
            (byte) 0xB0, (byte) 0xCA, (byte) 0xAF, (byte) 0xBC,
            (byte) 0x90, (byte) 0x8F, (byte) 0xEA, (byte) 0xFA,
            (byte) 0xBE, (byte) 0xA0, (byte) 0xB6, (byte) 0xB3,
            (byte) 0x9D, (byte) 0xDA, (byte) 0x9B, (byte) 0x8B,
            (byte) 0xB7, (byte) 0xB8, (byte) 0xB9, (byte) 0xAB,
            (byte) 0x64, (byte) 0x65, (byte) 0x62, (byte) 0x66,
            (byte) 0x63, (byte) 0x67, (byte) 0x9E, (byte) 0x68,
            (byte) 0x74, (byte) 0x71, (byte) 0x72, (byte) 0x73,
            (byte) 0x78, (byte) 0x75, (byte) 0x76, (byte) 0x77,
            (byte) 0xAC, (byte) 0x69, (byte) 0xED, (byte) 0xEE,
            (byte) 0xEB, (byte) 0xEF, (byte) 0xEC, (byte) 0xBF,
            (byte) 0x80, (byte) 0xFD, (byte) 0xFE, (byte) 0xFB,
            (byte) 0xFC, (byte) 0xBA, (byte) 0xAE, (byte) 0x59,
            (byte) 0x44, (byte) 0x45, (byte) 0x42, (byte) 0x46,
            (byte) 0x43, (byte) 0x47, (byte) 0x9C, (byte) 0x48,
            (byte) 0x54, (byte) 0x51, (byte) 0x52, (byte) 0x53,
            (byte) 0x58, (byte) 0x55, (byte) 0x56, (byte) 0x57,
            (byte) 0x8C, (byte) 0x49, (byte) 0xCD, (byte) 0xCE,
            (byte) 0xCB, (byte) 0xCF, (byte) 0xCC, (byte) 0xE1,
            (byte) 0x70, (byte) 0xDD, (byte) 0xDE, (byte) 0xDB,
            (byte) 0xDC, (byte) 0x8D, (byte) 0x8E, (byte) 0xDF
    };
    public static final byte STX = 0x02;
    public static final byte FS = 0x1C;
    public static final byte US = 0x1F;
    public static final byte RS = 0x1D;
    public static final byte GS = 0x1E;
    public static final byte ETX = 0x03;

    public static String ebcdicToAscii(byte[] e) {
        return new String(ebcdicToAsciiBytes(e, 0, e.length), CHARSET);
    }

    public static String ebcdicToAscii(byte[] e, int offset, int len) {
        return new String(ebcdicToAsciiBytes(e, offset, len), CHARSET);
    }

    public static byte[] ebcdicToAsciiBytes(byte[] e) {
        return ebcdicToAsciiBytes(e, 0, e.length);
    }

    public static byte[] ebcdicToAsciiBytes(byte[] e, int offset, int len) {
        byte[] a = new byte[len];
        for (int i = 0; i < len; i++) {
            a[i] = EBCDIC2ASCII[e[offset + i] & 0xFF];
		}
        return a;
    }

    public static byte[] asciiToEbcdic(String s) {
        int len = s.length();
        byte[] b = new byte[len];
        for (int i = 0; i < len; i++){
            b[i] = ASCII2EBCDIC[s.charAt(i) & 0xFF];
		}
        return b;
    }

    public static byte[] asciiToEbcdic(byte[] a) {
        byte[] e = new byte[a.length];
        for (int i = 0; i < a.length; i++) {
            e[i] = ASCII2EBCDIC[a[i] & 0xFF];
		}
        return e;
    }

    public static void asciiToEbcdic(String s, byte[] e, int offset) {
        int len = s.length();
        for (int i = 0; i < len; i++) {
            e[offset + i] = ASCII2EBCDIC[s.charAt(i) & 0xFF];
		}
    }

    public static void asciiToEbcdic(byte[] s, byte[] e, int offset) {
        int len = s.length;
        for (int i = 0; i < len; i++) {
            e[offset + i] = ASCII2EBCDIC[s[i]];
		}
    }

    /**
     * pad to the left
     *
     * @param s   - original string
     * @param len - desired len
     * @param c   - padding char
     * @return padded string
     * @throws RuntimeException on error
     */
    public static String padleft(String s, int len, char c)
            throws RuntimeException {
        s = s.trim();
        if (s.length() > len) {
            throw new RuntimeException("invalid len " + s.length() + "/" + len);
		}
        StringBuilder d = new StringBuilder(len);
        int fill = len - s.length();
        while (fill-- > 0) {
            d.append(c);
		}
        d.append(s);
        return d.toString();
    }

    /**
     * pad to the right
     *
     * @param s   -
     *            original string
     * @param len -
     *            desired len
     * @param c   -
     *            padding char
     * @return padded string
     */
    public static String padright(String s, int len, char c)  {
        s = s.trim();
        if (s.length() > len) {
            throw new RuntimeException("invalid len " + s.length() + "/" + len);
		}
        StringBuilder d = new StringBuilder(len);
        int fill = len - s.length();
        d.append(s);
        while (fill-- > 0) {
            d.append(c);
		}
        return d.toString();
    }

    /**
     * trim String (if not null)
     *
     * @param s String to trim
     * @return String (may be null)
     */
    public static String trim(String s) {
        return s != null ? s.trim() : null;
    }

    /**
     * left pad with '0'
     *
     * @param s   - original string
     * @param len - desired len
     * @return zero padded string
     */
    public static String zeropad(String s, int len)  {
        return padleft(s, len, '0');
    }

    /**
     * zeropads a long without throwing an RuntimeException (performs modulus operation)
     *
     * @param l   the long
     * @param len the length
     * @return zeropadded value
     */
    public static String zeropad(long l, int len) {
        try {
            return padleft(Long.toString((long) (l % Math.pow(10, len))), len, '0');
        } catch (RuntimeException ignored) {
        }
        return null; // should never happen
    }

    /**
     * pads to the right
     *
     * @param s   - original string
     * @param len - desired len
     * @return space padded string
     */
    public static String strpad(String s, int len) {
        StringBuilder d = new StringBuilder(s);
        while (d.length() < len) {
            d.append(' ');
		}
        return d.toString();
    }

    public static String zeropadRight(String s, int len) {
        StringBuilder d = new StringBuilder(s);
        while (d.length() < len) {
            d.append('0');
		}
        return d.toString();
    }

    /**
     * converts to BCD
     *
     * @param s       - the number
     * @param padLeft - flag indicating left/right padding
     * @param d       The byte array to copy into.
     * @param offset  Where to start copying into.
     * @return BCD representation of the number
     */
    public static byte[] str2bcd(String s, boolean padLeft, byte[] d, int offset) {
        int len = s.length();
        int start = (len & 1) == 1 && padLeft ? 1 : 0;
        for (int i = start; i < len + start; i++) {
            d[offset + (i >> 1)] |= s.charAt(i - start) - '0' << ((i & 1) == 1 ? 0 : 4);
		}
        return d;
    }

    /**
     * converts to BCD
     *
     * @param s       - the number
     * @param padLeft - flag indicating left/right padding
     * @return BCD representation of the number
     */
    public static byte[] str2bcd(String s, boolean padLeft) {
        int len = s.length();
        byte[] d = new byte[len + 1 >> 1];
        return str2bcd(s, padLeft, d, 0);
    }

    /**
     * converts to BCD
     *
     * @param s       - the number
     * @param padLeft - flag indicating left/right padding
     * @param fill    - fill value
     * @return BCD representation of the number
     */
    public static byte[] str2bcd(String s, boolean padLeft, byte fill) {
        int len = s.length();
        byte[] d = new byte[len + 1 >> 1];
        Arrays.fill(d, fill);
        int start = (len & 1) == 1 && padLeft ? 1 : 0;
        for (int i = start; i < len + start; i++) {
            d[i >> 1] |= s.charAt(i - start) - '0' << ((i & 1) == 1 ? 0 : 4);
		}
        return d;
    }

    /**
     * converts a BCD representation of a number to a String
     *
     * @param b       - BCD representation
     * @param offset  - starting offset
     * @param len     - BCD field len
     * @param padLeft - was padLeft packed?
     * @return the String representation of the number
     */
    public static String bcd2str(byte[] b, int offset,
                                 int len, boolean padLeft) {
        StringBuilder d = new StringBuilder(len);
        int start = (len & 1) == 1 && padLeft ? 1 : 0;
        for (int i = start; i < len + start; i++) {
            int shift = (i & 1) == 1 ? 0 : 4;
            char c = Character.forDigit(
                    b[offset + (i >> 1)] >> shift & 0x0F, 16);
            if (c == 'd') {
                c = '=';
			}
            d.append(Character.toUpperCase(c));
        }
        return d.toString();
    }

    /**
     * converts a byte array to hex string
     * (suitable for dumps and ASCII packaging of Binary fields
     *
     * @param b - byte array
     * @return String representation
     */
    public static String hexString(byte[] b) {
        StringBuilder d = new StringBuilder(b.length * 2);
        for (byte aB : b) {
            d.append(hexStrings[(int) aB & 0xFF]);
        }
        return d.toString();
    }

    /**
     * converts a byte array to printable characters
     *
     * @param b - byte array
     * @return String representation
     */
    public static String dumpString(byte[] b) {
        StringBuilder d = new StringBuilder(b.length * 2);
        for (byte aB : b) {
            char c = (char) aB;
            if (Character.isISOControl(c)) {
                // TODO: complete list of control characters,
                // use a String[] instead of this weird switch
                switch (c) {
                    case '\r':
                        d.append("{CR}");
                        break;
                    case '\n':
                        d.append("{LF}");
                        break;
                    case '\000':
                        d.append("{NULL}");
                        break;
                    case '\001':
                        d.append("{SOH}");
                        break;
                    case '\002':
                        d.append("{STX}");
                        break;
                    case '\003':
                        d.append("{ETX}");
                        break;
                    case '\004':
                        d.append("{EOT}");
                        break;
                    case '\005':
                        d.append("{ENQ}");
                        break;
                    case '\006':
                        d.append("{ACK}");
                        break;
                    case '\007':
                        d.append("{BEL}");
                        break;
                    case '\020':
                        d.append("{DLE}");
                        break;
                    case '\025':
                        d.append("{NAK}");
                        break;
                    case '\026':
                        d.append("{SYN}");
                        break;
                    case '\034':
                        d.append("{FS}");
                        break;
                    case '\036':
                        d.append("{RS}");
                        break;
                    default:
                        d.append('[');
                        d.append(hexStrings[(int) aB & 0xFF]);
                        d.append(']');
                        break;
                }
            } else {
                d.append(c);
			}
        }
        return d.toString();
    }

    /**
     * converts a byte array to hex string
     * (suitable for dumps and ASCII packaging of Binary fields
     *
     * @param b      - byte array
     * @param offset - starting position
     * @param len    the length
     * @return String representation
     */
    public static String hexString(byte[] b, int offset, int len) {
        StringBuilder d = new StringBuilder(len * 2);
        len += offset;
        for (int i = offset; i < len; i++) {
            d.append(hexStrings[(int) b[i] & 0xFF]);
        }
        return d.toString();
    }

    /**
     * bit representation of a BitSet
     * suitable for dumps and debugging
     *
     * @param b - the BitSet
     * @return string representing the bits (i.e. 011010010...)
     */
    public static String bitSet2String(BitSet b) {
        int len = b.size();
        len = len > 128 ? 128 : len;
        StringBuilder d = new StringBuilder(len);
        for (int i = 0; i < len; i++) {
            d.append(b.get(i) ? '1' : '0');
		}
        return d.toString();
    }

    /**
     * converts a BitSet into a binary field
     * used in pack routines
     *
     * @param b - the BitSet
     * @return binary representation
     */
    public static byte[] bitSet2byte(BitSet b) {
        int len = b.length() + 62 >> 6 << 6;
        byte[] d = new byte[len >> 3];
        for (int i = 0; i < len; i++) {
            if (b.get(i + 1)) {
                d[i >> 3] |= 0x80 >> i % 8;
			}
		}
        if (len > 64) {
            d[0] |= 0x80;
		}
        if (len > 128) {
            d[8] |= 0x80;
		}
        return d;
    }

    /**
     * converts a BitSet into a binary field
     * used in pack routines
     *
     * @param b     - the BitSet
     * @param bytes - number of bytes to return
     * @return binary representation
     */
    public static byte[] bitSet2byte(BitSet b, int bytes) {
        int len = bytes * 8;

        byte[] d = new byte[bytes];
        for (int i = 0; i < len; i++) {
            if (b.get(i + 1)) {
                d[i >> 3] |= 0x80 >> i % 8;
			}
		}
        //TODO: review why 2nd & 3rd bit map flags are set here???
        if (len > 64) {
            d[0] |= 0x80;
		}
        if (len > 128) {
            d[8] |= 0x80;
		}
        return d;
    }

    /*
     * Convert BitSet to int value.
     */
    public static int bitSet2Int(BitSet bs) {
        int total = 0;
        int b = bs.length() - 1;
        if (b > 0) {
            int value = (int) Math.pow(2, b);
            for (int i = 0; i <= b; i++) {
                if (bs.get(i)) {
                    total += value;
				}
                value = value >> 1;
            }
        }

        return total;
    }

    /*
     * Convert int value to BitSet.
     */
    public static BitSet int2BitSet(int value) {

        return int2BitSet(value, 0);
    }

    /*
     * Convert int value to BitSet.
     */
    public static BitSet int2BitSet(int value, int offset) {

        BitSet bs = new BitSet();

        String hex = Integer.toHexString(value);
        hex2BitSet(bs, hex.getBytes(), offset);

        return bs;
    }

    /**
     * Converts a binary representation of a Bitmap field
     * into a Java BitSet
     *
     * @param b                    - binary representation
     * @param offset               - staring offset
     * @param bitZeroMeansExtended - true for ISO-8583
     * @return java BitSet object
     */
    public static BitSet byte2BitSet(byte[] b, int offset, boolean bitZeroMeansExtended) {
        int len = bitZeroMeansExtended ? (b[offset] & 0x80) == 0x80 ? 128 : 64 : 64;
        BitSet bmap = new BitSet(len);
        for (int i = 0; i < len; i++) {
            if ((b[offset + (i >> 3)] & 0x80 >> i % 8) > 0) {
                bmap.set(i + 1);
			}
		}
        return bmap;
    }

    /**
     * Converts a binary representation of a Bitmap field
     * into a Java BitSet
     *
     * @param b       - binary representation
     * @param offset  - staring offset
     * @param maxBits - max number of bits (supports 64,128 or 192)
     * @return java BitSet object
     */
    public static BitSet byte2BitSet(byte[] b, int offset, int maxBits) {
        int len = maxBits > 64 ? (b[offset] & 0x80) == 0x80 ? 128 : 64 : maxBits;

        if (maxBits > 128 && b.length > offset + 8
			&& (b[offset + 8] & 0x80) == 0x80) {
            len = 192;
        }
        BitSet bmap = new BitSet(len);
        for (int i = 0; i < len; i++) {
            if ((b[offset + (i >> 3)] & 0x80 >> i % 8) > 0) {
                bmap.set(i + 1);
			}
		}
        return bmap;
    }

    /**
     * Converts a binary representation of a Bitmap field
     * into a Java BitSet
     *
     * @param bmap      - BitSet
     * @param b         - hex representation
     * @param bitOffset - (i.e. 0 for primary bitmap, 64 for secondary)
     * @return java BitSet object
     */
    public static BitSet byte2BitSet(BitSet bmap, byte[] b, int bitOffset) {
        int len = b.length << 3;
        for (int i = 0; i < len; i++) {
            if ((b[i >> 3] & 0x80 >> i % 8) > 0) {
                bmap.set(bitOffset + i + 1);
			}
		}
        return bmap;
    }

    /**
     * Converts an ASCII representation of a Bitmap field
     * into a Java BitSet
     *
     * @param b                    - hex representation
     * @param offset               - starting offset
     * @param bitZeroMeansExtended - true for ISO-8583
     * @return java BitSet object
     */
    public static BitSet hex2BitSet(byte[] b, int offset, boolean bitZeroMeansExtended) {
        int len = bitZeroMeansExtended
			? (Character.digit((char) b[offset], 16) & 0x08) == 8 ? 128 : 64 : 64;
        BitSet bmap = new BitSet(len);
        for (int i = 0; i < len; i++) {
            int digit = Character.digit((char) b[offset + (i >> 2)], 16);
            if ((digit & 0x08 >> i % 4) > 0) {
                bmap.set(i + 1);
			}
        }
        return bmap;
    }

    /**
     * Converts an ASCII representation of a Bitmap field
     * into a Java BitSet
     *
     * @param b       - hex representation
     * @param offset  - starting offset
     * @param maxBits - max number of bits (supports 8, 16, 24, 32, 48, 52, 64,.. 128 or 192)
     * @return java BitSet object
     */
    public static BitSet hex2BitSet(byte[] b, int offset, int maxBits) {
        int len = maxBits > 64
			? (Character.digit((char) b[offset], 16) & 0x08) == 8 ? 128 : 64 : maxBits;
        if (len > 64 && maxBits > 128
			&& b.length > offset + 16
			&& (Character.digit((char) b[offset + 16], 16) & 0x08) == 8) {
            len = 192;
        }
        BitSet bmap = new BitSet(len);
        for (int i = 0; i < len; i++) {
            int digit = Character.digit((char) b[offset + (i >> 2)], 16);
            if ((digit & 0x08 >> i % 4) > 0) {
                bmap.set(i + 1);
                if (i == 65 && maxBits > 128) {
                    len = 192;
				}
            }
        }
        return bmap;
    }

    /**
     * Converts an ASCII representation of a Bitmap field
     * into a Java BitSet
     *
     * @param bmap      - BitSet
     * @param b         - hex representation
     * @param bitOffset - (i.e. 0 for primary bitmap, 64 for secondary)
     * @return java BitSet object
     */
    public static BitSet hex2BitSet(BitSet bmap, byte[] b, int bitOffset) {
        int len = b.length << 2;
        for (int i = 0; i < len; i++) {
            int digit = Character.digit((char) b[i >> 2], 16);
            if ((digit & 0x08 >> i % 4) > 0) {
                bmap.set(bitOffset + i + 1);
			}
        }
        return bmap;
    }

    /**
     * @param b      source byte array
     * @param offset starting offset
     * @param len    number of bytes in destination (processes len*2)
     * @return byte[len]
     */
    public static byte[] hex2byte(byte[] b, int offset, int len) {
        byte[] d = new byte[len];
        for (int i = 0; i < len * 2; i++) {
            int shift = i % 2 == 1 ? 0 : 4;
            d[i >> 1] |= Character.digit((char) b[offset + i], 16) << shift;
        }
        return d;
    }

    /**
     * Converts a hex string into a byte array
     *
     * @param s source string (with Hex representation)
     * @return byte array
     */
    public static byte[] hex2byte(String s) {
        if (s.length() % 2 == 0) {
            return hex2byte(s.getBytes(), 0, s.length() >> 1);
        } else {
            // Padding left zero to make it even size #Bug raised by tommy
            return hex2byte("0" + s);
        }
    }

    /**
     * Converts a byte array into a hex string
     *
     * @param bs source byte array
     * @return hexadecimal representation of bytes
     */
    public static String byte2hex(byte[] bs) {
        return byte2hex(bs, 0, bs.length);
    }

    /**
     * Converts an integer into a byte array of hex
     *
     * @param value
     * @return bytes representation of integer
     */
    public static byte[] int2byte(int value) {
        if (value < 0) {
            return new byte[]{(byte) (value >>> 24 & 0xFF), (byte) (value >>> 16 & 0xFF),
                    (byte) (value >>> 8 & 0xFF), (byte) (value & 0xFF)};
        } else if (value <= 0xFF) {
            return new byte[]{(byte) (value & 0xFF)};
        } else if (value <= 0xFFFF) {
            return new byte[]{(byte) (value >>> 8 & 0xFF), (byte) (value & 0xFF)};
        } else if (value <= 0xFFFFFF) {
            return new byte[]{(byte) (value >>> 16 & 0xFF), (byte) (value >>> 8 & 0xFF),
                    (byte) (value & 0xFF)};
        } else {
            return new byte[]{(byte) (value >>> 24 & 0xFF), (byte) (value >>> 16 & 0xFF),
                    (byte) (value >>> 8 & 0xFF), (byte) (value & 0xFF)};
        }
    }

    /**
     * Converts a byte array of hex into an integer
     *
     * @param bytes
     * @return integer representation of bytes
     */
    public static int byte2int(byte[] bytes) {
        if (bytes == null || bytes.length == 0) {
            return 0;
        }
        ByteBuffer byteBuffer = ByteBuffer.allocate(4);
        for (int i = 0; i < 4 - bytes.length; i++) {
            byteBuffer.put((byte) 0);
        }
		for (byte aByte : bytes) {
			byteBuffer.put(aByte);
		}
        byteBuffer.position(0);
        return byteBuffer.getInt();
    }

    /**
     * Converts a byte array into a string of lower case hex chars.
     *
     * @param bs     A byte array
     * @param off    The index of the first byte to read
     * @param length The number of bytes to read.
     * @return the string of hex chars.
     */
    public static String byte2hex(byte[] bs, int off, int length) {
        if (bs.length <= off || bs.length < off + length) {
            throw new IllegalArgumentException();
		}
        StringBuilder sb = new StringBuilder(length * 2);
        byte2hexAppend(bs, off, length, sb);
        return sb.toString();
    }

    private static void byte2hexAppend(byte[] bs, int off, int length, StringBuilder sb) {
        if (bs.length <= off || bs.length < off + length) {
            throw new IllegalArgumentException();
		}
        sb.ensureCapacity(sb.length() + length * 2);
        for (int i = off; i < off + length; i++) {
            sb.append(Character.forDigit(bs[i] >>> 4 & 0xf, 16));
            sb.append(Character.forDigit(bs[i] & 0xf, 16));
        }
    }

    /**
     * format double value
     *
     * @param d   the amount
     * @param len the field len
     * @return a String of fieldLen characters (right justified)
     */
    public static String formatDouble(double d, int len) {
        String prefix = Long.toString((long) d);
        String suffix = Integer.toString(
                (int) (Math.round(d * 100f) % 100));
        try {
            if (len > 3) {
                prefix = ISOUtil.padleft(prefix, len - 3, ' ');
			}
            suffix = ISOUtil.zeropad(suffix, 2);
        } catch (RuntimeException e) {
            // should not happen
        }
        return prefix + "." + suffix;
    }

    /**
     * prepare long value used as amount for display
     * (implicit 2 decimals)
     *
     * @param l   value
     * @param len display len
     * @return formated field
     */
    public static String formatAmount(long l, int len) {
        String buf = Long.toString(l);
        if (l < 100) {
            buf = zeropad(buf, 3);
		}
        StringBuilder s = new StringBuilder(padleft(buf, len - 1, ' '));
        s.insert(len - 3, '.');
        return s.toString();
    }

    /**
     * XML normalizer
     *
     * @param s         source String
     * @param canonical true if we want to normalize \r and \n as well
     * @return normalized string suitable for XML Output
     */
    public static String normalize(String s, boolean canonical) {
        StringBuilder str = new StringBuilder();

        int len = s != null ? s.length() : 0;
        for (int i = 0; i < len; i++) {
            char ch = s.charAt(i);
            switch (ch) {
                case '<':
                    str.append("&lt;");
                    break;
                case '>':
                    str.append("&gt;");
                    break;
                case '&':
                    str.append("&amp;");
                    break;
                case '"':
                    str.append("&quot;");
                    break;
                case '\r':
                case '\n':
                    if (canonical) {
                        str.append("&#");
                        str.append(Integer.toString(ch & 0xFF));
                        str.append(';');
                        break;
                    }
                    // else, default append char
                default:
                    if (ch < 0x20) {
                        str.append("&#");
                        str.append(Integer.toString(ch & 0xFF));
                        str.append(';');
                    } else if (ch > 0xff00) {
                        str.append((char) (ch & 0xFF));
                    } else {
                        str.append(ch);
					}
            }
        }
        return str.toString();
    }

    /**
     * XML normalizer (default canonical)
     *
     * @param s source String
     * @return normalized string suitable for XML Output
     */
    public static String normalize(String s) {
        return normalize(s, true);
    }

    /**
     * Protects PAN, Track2, CVC (suitable for logs).
     * <p/>
     * <pre>
     * "40000101010001" is converted to "400001____0001"
     * "40000101010001=020128375" is converted to "400001____0001=0201_____"
     * "40000101010001D020128375" is converted to "400001____0001D0201_____"
     * "123" is converted to "___"
     * </pre>
     *
     * @param s string to be protected
     * @return 'protected' String
     */
    public static String protect(String s) {
        StringBuilder sb = new StringBuilder();
        int len = s.length();
        int clear = len > 6 ? 6 : 0;
        int lastFourIndex = -1;
        if (clear > 0) {
            lastFourIndex = s.indexOf('=') - 4;
            if (lastFourIndex < 0) {
                lastFourIndex = s.indexOf('^') - 4;
			}
            if (lastFourIndex < 0 && s.indexOf('^') < 0) {
                lastFourIndex = s.indexOf('D') - 4;
			}
            if (lastFourIndex < 0) {
                lastFourIndex = len - 4;
			}
        }
        for (int i = 0; i < len; i++) {
            if (s.charAt(i) == '=' || s.charAt(i) == 'D' && s.indexOf('^') < 0) {
                clear = 1;  // use clear=5 to keep the expiration date
			} else if (s.charAt(i) == '^') {
                lastFourIndex = 0;
                clear = len - i;
            } else if (i == lastFourIndex) {
                clear = 4;
			}
            sb.append(clear-- > 0 ? s.charAt(i) : '_');
        }
        s = sb.toString();
        try {
            //Addresses Track1 Truncation
            int charCount = s.replaceAll("[^\\^]", "").length();
            if (charCount == 2) {
                s = s.substring(0, s.lastIndexOf("^") + 1);
                s = ISOUtil.padright(s, len, '_');
            }
        } catch (RuntimeException e) {
            //cannot PAD - should never get here
        }
        return s;
    }

    public static int[] toIntArray(String s) {
        StringTokenizer st = new StringTokenizer(s);
        int[] array = new int[st.countTokens()];
        for (int i = 0; st.hasMoreTokens(); i++) {
            array[i] = Integer.parseInt(st.nextToken());
		}
        return array;
    }

    public static String[] toStringArray(String s) {
        StringTokenizer st = new StringTokenizer(s);
        String[] array = new String[st.countTokens()];
        for (int i = 0; st.hasMoreTokens(); i++) {
            array[i] = st.nextToken();
		}
        return array;
    }

    /**
     * Bitwise XOR between corresponding bytes
     *
     * @param op1 byteArray1
     * @param op2 byteArray2
     * @return an array of length = the smallest between op1 and op2
     */
    public static byte[] xor(byte[] op1, byte[] op2) {
        byte[] result;
        // Use the smallest array
        if (op2.length > op1.length) {
            result = new byte[op1.length];
        } else {
            result = new byte[op2.length];
        }
        for (int i = 0; i < result.length; i++) {
            result[i] = (byte) (op1[i] ^ op2[i]);
        }
        return result;
    }

    /**
     * Bitwise XOR between corresponding byte arrays represented in hex
     *
     * @param op1 hexstring 1
     * @param op2 hexstring 2
     * @return an array of length = the smallest between op1 and op2
     */
    public static String hexor(String op1, String op2) {
        byte[] xor = xor(hex2byte(op1), hex2byte(op2));
        return hexString(xor);
    }

    /**
     * Trims a byte[] to a certain length
     *
     * @param array  the byte[] to be trimmed
     * @param length the wanted length
     * @return the trimmed byte[]
     */
    public static byte[] trim(byte[] array, int length) {
        byte[] trimmedArray = new byte[length];
        System.arraycopy(array, 0, trimmedArray, 0, length);
        return trimmedArray;
    }

    /**
     * Concatenates two byte arrays (array1 and array2)
     *
     * @param array1 first part
     * @param array2 last part
     * @return the concatenated array
     */
    public static byte[] concat(byte[] array1, byte[] array2) {
        byte[] concatArray = new byte[array1.length + array2.length];
        System.arraycopy(array1, 0, concatArray, 0, array1.length);
        System.arraycopy(array2, 0, concatArray, array1.length, array2.length);
        return concatArray;
    }

    /**
     * Concatenates two byte arrays (array1 and array2)
     *
     * @param array1      first part
     * @param beginIndex1 initial index
     * @param length1     length
     * @param array2      last part
     * @param beginIndex2 last part index
     * @param length2     last part length
     * @return the concatenated array
     */
    public static byte[] concat(byte[] array1, int beginIndex1, int length1, byte[] array2,
                                int beginIndex2, int length2) {
        byte[] concatArray = new byte[length1 + length2];
        System.arraycopy(array1, beginIndex1, concatArray, 0, length1);
        System.arraycopy(array2, beginIndex2, concatArray, length1, length2);
        return concatArray;
    }

    /**
     * Causes the currently executing thread to sleep (temporarily cease
     * execution) for the specified number of milliseconds. The thread
     * does not lose ownership of any monitors.
     * <p/>
     * This is the same as Thread.sleep () without throwing InterruptedException
     *
     * @param millis the length of time to sleep in milliseconds.
     */
    public static void sleep(long millis) {
        try {
            Thread.sleep(millis);
        } catch (InterruptedException ignored) {
        }
    }

    /**
     * Left unPad with '0'
     *
     * @param s - original string
     * @return zero unPadded string
     */
    public static String zeroUnPad(String s) {
        return unPadLeft(s, '0');
    }

    /**
     * Right unPad with ' '
     *
     * @param s - original string
     * @return blank unPadded string
     */
    public static String blankUnPad(String s) {
        return unPadRight(s, ' ');
    }

    /**
     * Unpad from right.
     *
     * @param s - original string
     * @param c - padding char
     * @return unPadded string.
     */
    public static String unPadRight(String s, char c) {
        int end = s.length();
        if (end == 0) {
            return s;
		}
        while (0 < end && s.charAt(end - 1) == c) {
        	end--;
		}
        return 0 < end ? s.substring(0, end) : s.substring(0, 1);
    }

    /**
     * Unpad from left.
     *
     * @param s - original string
     * @param c - padding char
     * @return unPadded string.
     */
    public static String unPadLeft(String s, char c) {
        int fill = 0, end = s.length();
        if (end == 0) {
            return s;
		}
        while (fill < end && s.charAt(fill) == c) {
        	fill++;
		}
        return fill < end ? s.substring(fill, end) : s.substring(fill - 1, end);
    }

    /**
     * @return true if the string is zero-filled ( 0 char filled )
     */
    public static boolean isZero(String s) {
        int i = 0, len = s.length();
        while (i < len && s.charAt(i) == '0') {
            i++;
        }
        return i >= len;
    }

    /**
     * @return true if the string is blank filled (space char filled)
     */
    public static boolean isBlank(String s) {
        return s.trim().length() == 0;
    }

    /**
     * Return true if the string is alphanum.
     * <code>{letter digit (.) (_) (-) ( ) (?) }</code>
     */
    public static boolean isAlphaNumeric(String s) {
        int i = 0, len = s.length();
        while (i < len && (Character.isLetterOrDigit(s.charAt(i))
			|| s.charAt(i) == ' ' || s.charAt(i) == '.'
			|| s.charAt(i) == '-' || s.charAt(i) == '_')
			|| s.charAt(i) == '?') {
            i++;
        }
        return i >= len;
    }

    /**
     * Return true if the string represent a number
     * in the specified radix.
     * <br><br>
     */
    public static boolean isNumeric(String s, int radix) {
        int i = 0, len = s.length();
        while (i < len && Character.digit(s.charAt(i), radix) > -1) {
            i++;
        }
        return i >= len && len > 0;
    }

    /**
     * Converts a BitSet into an extended binary field
     * used in pack routines. The result is always in the
     * extended format: (16 bytes of length)
     * <br><br>
     *
     * @param b the BitSet
     * @return binary representation
     */
    public static byte[] bitSet2extendedByte(BitSet b) {
        int len = 128;
        byte[] d = new byte[len >> 3];
        for (int i = 0; i < len; i++) {
            if (b.get(i + 1)) {
                d[i >> 3] |= 0x80 >> i % 8;
			}
		}
        d[0] |= 0x80;
        return d;
    }

    /**
     * Converts a String to an integer of base radix.
     * <br><br>
     * String constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param s     String representation of number
     * @param radix Number base to use
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(String s, int radix) throws NumberFormatException {
        int length = s.length();
        if (length > 9) {
            throw new NumberFormatException("Number can have maximum 9 digits");
		}
        int result;
        int index = 0;
        int digit = Character.digit(s.charAt(index++), radix);
        if (digit == -1) {
            throw new NumberFormatException("String contains non-digit");
		}
        result = digit;
        while (index < length) {
            result *= radix;
            digit = Character.digit(s.charAt(index++), radix);
            if (digit == -1) {
                throw new NumberFormatException("String contains non-digit");
			}
            result += digit;
        }
        return result;
    }

    /**
     * Converts a String to an integer of radix 10.
     * <br><br>
     * String constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param s String representation of number
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(String s) throws NumberFormatException {
        return parseInt(s, 10);
    }

    /**
     * Converts a character array to an integer of base radix.
     * <br><br>
     * Array constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param cArray Character Array representation of number
     * @param radix  Number base to use
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(char[] cArray, int radix) throws NumberFormatException {
        int length = cArray.length;
        if (length > 9) {
            throw new NumberFormatException("Number can have maximum 9 digits");
		}
        int result;
        int index = 0;
        int digit = Character.digit(cArray[index++], radix);
        if (digit == -1) {
            throw new NumberFormatException("Char array contains non-digit");
		}
        result = digit;
        while (index < length) {
            result *= radix;
            digit = Character.digit(cArray[index++], radix);
            if (digit == -1) {
                throw new NumberFormatException("Char array contains non-digit");
			}
            result += digit;
        }
        return result;
    }

    /**
     * Converts a character array to an integer of radix 10.
     * <br><br>
     * Array constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param cArray Character Array representation of number
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(char[] cArray) throws NumberFormatException {
        return parseInt(cArray, 10);
    }

    /**
     * Converts a byte array to an integer of base radix.
     * <br><br>
     * Array constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param bArray Byte Array representation of number
     * @param radix  Number base to use
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(byte[] bArray, int radix) throws NumberFormatException {
        int length = bArray.length;
        if (length > 9) {
            throw new NumberFormatException("Number can have maximum 9 digits");
		}
        int result;
        int index = 0;
        int digit = Character.digit((char) bArray[index++], radix);
        if (digit == -1) {
            throw new NumberFormatException("Byte array contains non-digit");
		}
        result = digit;
        while (index < length) {
            result *= radix;
            digit = Character.digit((char) bArray[index++], radix);
            if (digit == -1) {
                throw new NumberFormatException("Byte array contains non-digit");
			}
            result += digit;
        }
        return result;
    }

    /**
     * Converts a byte array to an integer of radix 10.
     * <br><br>
     * Array constraints are:
     * <li>Number must be less than 10 digits</li>
     * <li>Number must be positive</li>
     *
     * @param bArray Byte Array representation of number
     * @return integer value of number
     * @throws NumberFormatException
     */
    public static int parseInt(byte[] bArray) throws NumberFormatException {
        return parseInt(bArray, 10);
    }

    private static String hexOffset(int i) {
        i = i >> 4 << 4;
        int w = i > 0xFFFF ? 8 : 4;
        try {
            return zeropad(Integer.toString(i, 16), w);
        } catch (RuntimeException e) {
            // should not happen
            return e.getMessage();
        }
    }

    /**
     * @param b a byte[] buffer
     * @return hexdump
     */
    public static String hexdump(byte[] b) {
        return hexdump(b, 0, b.length);
    }

    /**
     * @param b      a byte[] buffer
     * @param offset starting offset
     */
    public static String hexdump(byte[] b, int offset) {
        return hexdump(b, offset, b.length - offset);
    }

    /**
     * @param b      a byte[] buffer
     * @param offset starting offset
     * @param len    the Length
     * @return hexdump
     */
    public static String hexdump(byte[] b, int offset, int len) {
        StringBuilder sb = new StringBuilder();
        StringBuilder hex = new StringBuilder();
        StringBuilder ascii = new StringBuilder();
        String sep = "  ";
        String lineSep = System.getProperty("line.separator");
        len = offset + len;

        for (int i = offset; i < len; i++) {
            hex.append(hexStrings[(int) b[i] & 0xFF]);
            hex.append(' ');
            char c = (char) b[i];
            ascii.append(c >= 32 && c < 127 ? c : '.');

            int j = i % 16;
            switch (j) {
                case 7:
                    hex.append(' ');
                    break;
                case 15:
                    sb.append(hexOffset(i));
                    sb.append(sep);
                    sb.append(hex.toString());
                    sb.append(' ');
                    sb.append(ascii.toString());
                    sb.append(lineSep);
                    hex = new StringBuilder();
                    ascii = new StringBuilder();
                    break;
				default:
            }
        }
        if (hex.length() > 0) {
            while (hex.length() < 49) {
                hex.append(' ');
			}

            sb.append(hexOffset(len));
            sb.append(sep);
            sb.append(hex.toString());
            sb.append(' ');
            sb.append(ascii.toString());
            sb.append(lineSep);
        }
        return sb.toString();
    }

    /**
     * pads a string with 'F's (useful for pinoffset management)
     *
     * @param s   an [hex]string
     * @param len desired length
     * @return string right padded with 'F's
     */
    public static String strpadf(String s, int len) {
        StringBuilder d = new StringBuilder(s);
        while (d.length() < len) {
            d.append('F');
		}
        return d.toString();
    }

    /**
     * reverse the effect of strpadf
     *
     * @param s F padded string
     * @return trimmed string
     */
    public static String trimf(String s) {
        if (s != null) {
            int l = s.length();
            if (l > 0) {
                while (--l >= 0) {
                    if (s.charAt(l) != 'F') {
                        break;
					}
                }
                s = l == 0 ? "" : s.substring(0, l + 1);
            }
        }
        return s;
    }

    /**
     * return the last n characters of the passed String, left padding where required with 0
     *
     * @param s String to take from
     * @param n nuber of characters to take
     * @return String (may be null)
     */
    public static String takeLastN(String s, int n) {
        if (s.length() > n) {
            return s.substring(s.length() - n);
        } else {
            if (s.length() < n) {
                return zeropad(s, n);
            } else {
                return s;
            }
        }
    }

    /**
     * return the first n characters of the passed String, left padding where required with 0
     *
     * @param s String to take from
     * @param n nuber of characters to take
     * @return String (may be null)
     */
    public static String takeFirstN(String s, int n) {
        if (s.length() > n) {
            return s.substring(0, n);
        } else {
            if (s.length() < n) {
                return zeropad(s, n);
            } else {
                return s;
            }
        }
    }

    public static String millisToString(long millis) {
        StringBuilder sb = new StringBuilder();
        int ms = (int) (millis % 1000);
        millis /= 1000;
        int dd = (int) (millis / 86400);
        millis -= dd * 86400;
        int hh = (int) (millis / 3600);
        millis -= hh * 3600;
        int mm = (int) (millis / 60);
        millis -= mm * 60;
        int ss = (int) millis;
        if (dd > 0) {
            sb.append(Long.toString(dd));
            sb.append("d ");
        }
        sb.append(zeropad(hh, 2));
        sb.append(':');
        sb.append(zeropad(mm, 2));
        sb.append(':');
        sb.append(zeropad(ss, 2));
        sb.append('.');
        sb.append(zeropad(ms, 3));
        return sb.toString();
    }

    /**
     * Format a string containing a amount conversion rate in the proper format
     * <p/>
     * Format:
     * The leftmost digit (i.e., position 1) of this data element denotes the number of
     * positions the decimal separator must be moved from the right. Positions 2–8 of
     * this data element specify the rate. For example, a conversion rate value of
     * 91234567 in this data element would equate to 0.001234567.
     *
     * @param convRate - amount conversion rate
     * @return a string containing a amount conversion rate in the proper format,
     * witch is suitable for create fields 10 and 11
     */
    public static String formatAmountConversionRate(double convRate) {
        if (convRate == 0) {
            return null;
		}
        BigDecimal cr = new BigDecimal(convRate);
        int x = 7 - cr.precision() + cr.scale();
        String bds = cr.movePointRight(cr.scale()).toString();
        if (x > 9) {
            bds = ISOUtil.zeropad(bds, bds.length() + x - 9);
		}
        String ret = ISOUtil.zeropadRight(bds, 7);
        return Math.min(9, x) + ISOUtil.takeFirstN(ret, 7);
    }

    /**
     * Parse currency amount conversion rate string
     * <p/>
     * Suitble for parse fields 10 and 11
     *
     * @param convRate amount conversation rate
     * @return parsed currency amount conversation rate
     * @throws IllegalArgumentException
     */
    public static double parseAmountConversionRate(String convRate) {
        if (convRate == null || convRate.length() != 8)
            throw new IllegalArgumentException("Invalid amount converion rate argument: '" +
                    convRate + "'");
        BigDecimal bd = new BigDecimal(convRate);
        int pow = bd.movePointLeft(7).intValue();
        bd = new BigDecimal(convRate.substring(1));
        return bd.movePointLeft(pow).doubleValue();
    }

    /**
     * Converts a string[] into a comma-delimited String.
     * <p/>
     * Takes care of escaping commas using a backlash
     *
     * @param ss string array to be comma encoded
     * @return comma encoded string
     */
    public static String commaEncode(String[] ss) {
        StringBuilder sb = new StringBuilder();
        for (String s : ss) {
            if (sb.length() > 0) {
                sb.append(',');
			}
            if (s != null) {
                for (int i = 0; i < s.length(); i++) {
                    char c = s.charAt(i);
                    switch (c) {
                        case '\\':
                        case ',':
                            sb.append('\\');
                            break;
						default:
                    }
                    sb.append(c);
                }
            }
        }
        return sb.toString();
    }

    /**
     * Decodes a comma encoded String as encoded by commaEncode
     *
     * @param s the command encoded String
     * @return String[]
     */
    public static String[] commaDecode(String s) {
        List<String> l = new ArrayList<String>();
        StringBuilder sb = new StringBuilder();
        boolean escaped = false;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (!escaped) {
                switch (c) {
                    case '\\':
                        escaped = true;
                        continue;
                    case ',':
                        l.add(sb.toString());
                        sb = new StringBuilder();
                        continue;
					default:
                }
            }
            sb.append(c);
            escaped = false;
        }
        if (sb.length() > 0) {
            l.add(sb.toString());
		}
        return l.toArray(new String[l.size()]);
    }

    /**
     * Decodes a comma encoded String returning element in position i
     *
     * @param s comma encoded string
     * @param i position (starts at 0)
     * @return element in position i of comma encoded string, or null
     */
    public static String commaDecode(String s, int i) {
        String[] ss = commaDecode(s);
        int l = ss.length;
        return i >= 0 && i < l ? ss[i] : null;
    }

    /**
     * Compute card's check digit (LUHN)
     *
     * @param p PAN (without checkdigit)
     * @return the checkdigit
     */
    public static char calcLUHN(String p) {
        int i, crc;
        int odd = p.length() % 2;

        for (i = crc = 0; i < p.length(); i++) {
            char c = p.charAt(i);
            if (!Character.isDigit(c)) {
                throw new IllegalArgumentException("Invalid PAN " + p);
            }
            c = (char) (c - '0');
            if (i % 2 != odd) {
                crc += c * 2 >= 10 ? c * 2 - 9 : c * 2;
			} else {
                crc += c;
			}
        }

        return (char) ((crc % 10 == 0 ? 0 : 10 - crc % 10) + '0');
    }

    public static String getRandomDigits(Random r, int l, int radix) {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < l; i++) {
            sb.append(r.nextInt(radix));
        }
        return sb.toString();
    }

	/**
	 * unicode -> utf-8
	 * @param str unicode字符串
	 * @return utf-8字符串
	 */
	public static String unicode2String(String str) {
		Matcher matcher = UNICODE_2_STRING_PATTERN.matcher(str);
		while (matcher.find()) {
			char ch = (char) Integer.parseInt(matcher.group(2), 16);
			str = str.replace(matcher.group(1), ch + "");
		}
		return str;
	}

	private static final Pattern UNICODE_2_STRING_PATTERN = Pattern.compile("(\\\\u(\\p{XDigit}{4}))");
}
